Carburetor



Feb. 6, 1934. z 5 HOFFMAN 1,945,609

ICARBURETOR Filed March 4, 1930 2 Sheets-Sheet l J7 J2 Z ATTORNEY Patented Feb. 6, 1934 CARB URETOR Zachariah S. Hoffman, Essex County, N. J.

Application March 4, 1930. Serial No. 433,020

9 Claims.

My invention relates to carburetors for internal combustion engines, and has for an object to provide a carburetor of high eificiency in service.

The invention is particularly adapted for use on motor cars, but is also applicable to other vehicles such as airplanes, dirigibles, motorboats, etc., and an object of the invention is to provide means controlled by the speed of the vehicle for forcing air into the mixing chamber of the carburetor. With carburetor systems as heretofore designed, when the vehicle is traveling at high speed a high degree of suction is produced in the carburetor, drawing an excessive amount of fuel into the mixing chamber and producing a richer fuel mixture than is requisite. By my invention, a high suction drag is avoided thereby promoting economy in fuel consumption.

Another object of the invention is to provide means governed by the speed of the engine for automatically throttling the fuel inlet into the carburetor, so that as the speed of the engine rises and the velocity of the fluid current through the carburetor is increased the fuel inlet will be proportionately throttled.

Another object is to provide means control-' lable by the operator for, simultaneously varying the air feed and the fuel feed into the mixing chamber of the carburetor, the automatic control of the fuel feed referred to in the preceding paragraph being superimposed upon the control by the operator.

Another object is to provide manually operable means for adjusting the range of the fuel feed into the carburetor.

Another object is to provide means for preheating a part of the air admitted into the carburetor. g

Another object is to provide a thermostatic control of the temperature of the air fed into the carburetor.

Another object is to provide means for introducing cool as well as heated air into the carburetor with means controllable by the operator for varying the proportion of cool to heated air.

Another object is to provide a novel spray nozzle for introducing liquid fuel into the carburetor, so as to promote rapid and thorough vaporization. 7

These and other objects will appear in the following description of a preferred embodiment of my invention and thereafter the novelty and scope of the invention will be pointed out in the claims.

In the accompanying drawings;

[Figure 1 is a view in side elevation showing my improved carburetor installed on an automobile engine and showing means for feeding air thereto'through the radiator of the automobile, the radiator being partly broken away;

Fig. 2 is a front elevation of the radiator;

Fig. 3 is a view in longitudinal section through conduits connecting the radiator and carburetor;

Fig. 4 is a plan view of a portion of Fig. 3;

Fig. 5 is a view in section of one of the conduits, the section being taken on the line 5-5 of Fig. 3;

Fig. 6 is a view in side elevation of the carburetor, a portion thereof being shown in section;

Fig. 7 is a view in vertical section taken on the line 7-7 of Fig. 6;

Fig. 8 is a view in section on an enlarged scale, taken on the line 8--8 of Fig. 7, certain of the parts being shown in different position;

Fig. 9 is a view in section taken on the line 9--9 of Fig. 6 and showing an iris shutter in open position; and I I Fig. 10 is a plan view of the iris shutter shown in closed position.

In Figure 1, I show a portion of an automobile engine 15 provided with an intake manifold 16 and an exhaust manifold 1'7. My improved carburetor is shown at 18 connected to the intake manifold 16 in the usual manner. The radiator of the automobileis shown at'19, and, as clearly indicated in Fig. 2, there is an open slot 20 between the radiator proper and the shell 21 in which the radiator is housed. This slot is open on the forward side of the radiator but is closed at the rear. The slot extends around the top and two sides of the radiator proper. A pipe 22 runs across the rear of the radiator connecting the two vertical legs of the slot. Leading from the pipe 22 is a conduit 23 which extends past the exhaust manifold 17 to the carburetor 18. The conduit 23 is provided with an off-set branch 25 through which the exhaust manifold 17 passes, as shown clearly in Figs. 3 and 4, and for convenience the extension of conduit 23 past the branch 25 is indicated by the reference numeral 24. Leading from the lower end of the off-set branch 25 is a conduit 26 through which air heated by pipe 17 is conducted to the carburetor. Hereinafter the conduit 26 will be called the hot air pipe, while the extension 24, which draws little if any heat from the exhaust manifold, will be called the cold air pipe. A by-pass 27 connects the cold air pipe to the hot air pipe.

At the junction of the by-pas's 27 with the cold air pipe 26 there is a gate valve 28 which when swung in vertical position closes communication between the branch 25 and the hot air pipe, but opens the by-pass 27 to the hot air pipe. When this gate valve is raised to horizontal position, however, the by-pass is cut off from the hot air pipe. The position of the gate valve is controlled by a thermostat which is shown in Figs. 3 and 5. The thermostat comprises a plurality of thermostatic elements each consisting of a steel plate 30 to opposite sides of which zinc plates 31 are riveted. The zinc plates are slightly bulged at the center and are secured to the steel plates at their ends. Since zinc has a greater coefflcient of expansion than steel the bulging of the zinc plates will be increased as the thermostatic elements are heated. The thermostatic elements are strung upon a rod 32 which passes freely through openings in the center of the plates30 and 31. The rod has sliding support in bearings 33 and 33a located in the pipe 26. A compression spring 35 bears between a collar 36 at one end of the rod 32 and the bearing 33 and the thermostatic elements are yieldingly clamped between the bearing member 33 and a collar 34 fixed on the rod 32. The opposite end of the rod has pin-and-slot connection with a crank 37. This crank is secured to a shaft 38 which passes through the wall of the pipe 26 and has an arm 39 secured to the outer end thereof. This arm is connected at its free end by a link 40 to a crank 41 which is secured to the pivot pin 42 on which the gate valve 28 is fixed. The thermostat thus governs the temperature of the air drawn through the pipe 26. Normally the by-pass is cut off. When the engine is running the air drawn into pipe 26 is heated by the exhaust manifold 1'7 but as the temperature of the air rises the valve 28 will admit more-and-more cold air through the by-pass and less-and-less hot air from the branch 25 until a balance is struck 'or until the branch 25 is cut off altogether.

As shown in Fig. 5 the thermostatic elements are comparatively narrow and do not materially obstruct the clear passage through the pipe 26. The bearings 33 and 33a also are so designed as to provide ample clearance for the passage of air through the hot air pipe.

As shown in' Fig. 6, the pipe 24 communicates with a cold-air chamber formed by an outer shell 45 of the carburetor. A float chamber 46 is secured to or formed integrally with the shell 45. Within the chamber 46 is the usualfloat 47, controlling a valve 48 which admits liquid fuel into .the chamber 46 from the usual feed line 49. An

elbow fitting 50 is secured to the bottom of the shell 45 and provides communication between the pipe 26 and a hot-air chamber formed by a sleeve 51 within the shell 45. The fitting 50 is formed with a duct 52 which at one end communicates through a port 53 with the bottom of the float chamber 46, while at the other end, it communicates with a pipe 54 centrally disposed in the sleeve 51.

The upper end of the pipe 54 has a constricted opening or port 55 therein, as shown in Fig. 8, and a valve 56 is adapted to control said opening. The valve slides on a vertical rod 5'7 .and is taperedI at its upper end, so that as it is drawn up from the position shown in full lines in Fig. 8 to that shown in broken lines it will gradually close said port, but even when the valve is in the extreme raised position shown by broken lines, it does not completely close the port 55 but leaves a slight annular clearance for the passage of fuel.

The pipe 54 is provided at its upper end with a nozzle head comprising three radially projecting arms 58 which terminate at their outer ends in cups 59. These cups are preferably of triangular shape, as indicated in Fig. 9. I find that with triangular cups the vaporizing action is more effective than with cups having circular rims. However, I do not wish to limit myself to the useof. cups of triangular profile. Ducts 60 lead to the cups 59 from the port 55. The upper end of the sleeve is tapered inward to form a constricted mouth 61 which just clears the cups 59. The inner face of the shell 45 is also'tapered inward at its upper end to provide a'constricted mouth 62 for the .cold-air chamber.

Secured to the upper end of the shell 45 is a tubular fitting 63 within which is a mixing chamber 63a. The fitting 63 is provided at its lower end with a flange 64. The latter is recessed at its under-side to provide space for a cam disk 65 and an iris shutter located above the cam. The iris shutter is composed of a number of shutter plates 66 each of which is pivoted to the flange 64 at 67 and on each of which is provided a depending pin 68 engaging a slot 69 formed in the cam 65. By turning the cam 65 the plates may be swung on their pivots 67 to any position between the wide open position shown in Fig. 9, and the closed position shown in Fig. 10. The shutter plates when in closed position virtually engage the upper edge of the sleeve 51 and the upper edges of the cups 59 but provide annular clearance about the tubular stem 56a of the valve 56 through which air may be drawn from the hot air chamber and liquid fuel from the port 55. As the shutters are opened first the mouth 61 of the hot air chamber is uncovered and then the mouth 62 of the cold air chamber. The cam 65 is provided with an arm 70 at one end which passes through a slot '71 in the outer rim 72 of the flange 64. The arm 70 is formed with an arcuate recess 73 into which the rim 72 of the flange 64 enters, so as substantially to prevent leakage at this point. In other words,

.as shown in Fig. 7, the slot 71 is of less width bore 78 formed at one side of the fitting 63..

The other arm '79 of the lever '76 has pin and slot connection with a vertical rod 80 which slides in a guide 80a and which at its lower end carries a roller 81. to run on a cam 82 carried by the arm '70. A spring 83 holds the roller in engagement with the cam. The cam 82 consists of a curved strip which is higher at one end than the other, as shown in Fig. 6, so that as the arm '70 is op erated to open the iris shutter the roller will ride up the incline of cam 82 depressing the rod 57. The arm '70 is connected by a push rod 84 to a throttle lever or acceleratonpedal (not shown) and a spring acting on-the arm '70 tends to close the iris shutter.

Fitted between a pair of collars 85 and 86 The latter is adapted respectively (see Fig. 8) is a bearing member 87 which is freely rotatable on the rod 57. At the upper end of the tubular stem 56a of the valve 56 is cross-head 89. Links 90 are-pivotally connected to the cross-head 89 and links 91 are pivotally connected to the bearing member 8'7 and the links 90 and 91 are connected to each other by means of balls or weights 92. A compression spring 93fits between the crosshead 89 and asleeve member 94 and the latter is threaded into the bearing member 87. Clamped upon the bearing member 8'7 by a nut 96 is a fan 97. The construction just described will be recognized as a ball governor.

As the-fan 97 is rotated by the fluid stream passing through the mixing chamber 63a of the carburetor, the governor will operate to raise the valve 56 with respect to the rod 57.

The fulcrum of the lever '76 is vertically adjustable to adjust the range of movement of the valve 56 with respect to the port 55. The bar 77 is provided With'rack teeth which are engaged by a pinion 98 formed on the end of a shaft 99. The latter is connected by a knuckle joint 100 to an operating rod 101 which may run to the dash-board of the automobile. by turning the rod 101, the position of the fulcrum of the lever '76 may be vertically regulated.

The operation of the carburetor is as follows: In normal idling position, or when the engine is not running the roller 81 rests on the low end of the cam 82 permitting the spring 83 to lift the rod 57 so that the valve 56 is in closed position. This throttles the admission of fuel to the mixing chamber permitting only a slight amount of said fuel to enter said chamber through the annular clearance between the valve 56 and the port 55. At the same time the iris shutter is in the closed position shown in Fig. 10 covering the cups 59, cutting off the cold air supply and most of the heated air supply. The only air that is admitted to the mixing chamber is that which passes between the arms 58 of the nozzle and through the slight clearance between the ends of the shutter blades 66 and the valve stem 56oz. The engine draws air through said clearance sucking fuel through the port and mixing therewith in the usual manner to form the necessary fuel mixture for low or idling speeds. Since the air is heated the fuel will be immediately vaporized and thoroughly mixed with the air. As the throttle is manually opened (and by the term manually I mean to include foot as well as hand control) the cam 82 acting on the roller 81 depresses the valve 55 to admit correspondingly more fuel into the mixing chamber, and at the same time the cam causes the shutter blades 66 to open, admitting correspondingly more air into the mixing chamber. When the throttle is operated to such an extent that the shutter uncovers the cups 59 there will be a marked increase in the amount of fuel drawn into the mixing chamber because the air in fiowing past the cups produces an aspirating effect which draws fuel into the cups and this fuel is vaporized by the heated air and carried thereby into the mixing chamber. When the throttle is opened still further the mouth 62 is uncovered, admitting cold air into the mixing chamber. The influx of cold air promotes the mixing action and converts the fuel mixture into a mist. The flow of fluid through the mixing chamber causes rotation of the fan and as the velocity of the current through the mixing chamber rises the centrifugal governor operates to raise the valve 56 Thus,

and correspondingly throttle the feed of fuel. This results in reducing the richness of the fuel mixture. Excessive suction in the mixing chamber is obviated by providing large and substantially unobstructed conduits 24 and 26 for the admission of air and also by utilizing the pressure of the air against the face of the radiator to force air into the carburetor. To this extent the richness of the mixture is modified by the speed of the vehicle. I have thus provided an automatically operating carburetor which will adjust itself to running conditions and prevents too rich a mixture from entering the engine cylinders when the car is traveling at high speed. This effects an appreciable economy in fuel consumption.

It is to be noted that the va1ve56 is manually opened to increase the power of the engine, but the automatic closing of the valve depends on the speed and not the power of the engine. In other words, when the engine is called upon to performheavy work as in climbing hills or propelling a heavy load, the governor will not reduce the richness of the mixture. It is only when the speed of the engine exceeds a predetermined 100 rate that the automatic control begins to lower the valve 56.

When starting the car, particularly in cold weather, it is desirable to provide a richer fuel mixture, and this may be eifected by turning the rod 101 to lower the fulcrum of the lever '76. In fact, in winter weather it is desirable to use a richer range of fuel mixtures than in summer and this can be regulated by turning the rod. Varying the position of the fulcrum of lever 76 does not disturb the relative action of the manual and automatic controls but merely shifts the range of movement of the valve 56 and thereby shifts the range of fuel richness. The thermostat in the hot air tube prevents excessive heating of the air. In winter time it will cut off the by-pass 2'7 under normal conditions, while in summer time it will tend to cut off the heating chamber or branch pipe 25.

While I have described a preferred embodiment, it will be understood that this is to be taken as illustrative and not limitative of my invention, and that I reserve the right to make such allerations, variations and modifications in general form, details -of construction and arrangements of parts, as fall within the spirit and scope of the following claims.

I claim:

1. In a carburetor for an internal combustion engine, a. mixing chamber having an air inlet 130 and a fuel inlet, means for simultaneously opening and closing said inlets, and means actuated by mixture flow through the chamber for reducing the relative opening of the fuel inlet with respect to the air inlet as the rate of mixture 135 flow increases.

2. In a carburetor for an internal combustion engine, a mixing chamber having an air inlet and fuel inlet, means for simultaneously opening and closing said inlets, a fan in the mixing cham- 140 ber adapted to be driven by the current of fuel mixture drawn through the mixing chamber, a centrifugal governor driven by the fan, and means operable by the governor for reducing the relative'opening of the fuel inlet with respect to the 145 air inlet as the velocity of said current increases andfor increasing the relative opening of the fuel inlet with respect to the air inlet as the velocity of said current decreases.

3. In a carburetor for an internal combustion 150 engine, a mixing chamber, a fuel duct opening therein, a pair of air ducts concentric with the fuel duct and opening into said chamber, means for heating the air led into the inner air duct, a throttle valve in the fuel duct, an iris shutter for throttling the inlet of air from said air ducts into the chamber, means for operating said valve and shutter simultaneously, and means governed by the current of fuel mixture passing through said chamber for varying the opening of the valve with respect to the shutter.

4. In a carburetor for an internal combustion engine, a mixing chamber, a fuel duct opening therein, a pair of air ducts concentric with the fuel duct and opening into said chamber, means for heating the air led into the inner air duct, a throttle valve in the fuel duct, an iris shutter for throttling the inlet of air from said air ducts into the chamber, means for operating said valve and shutter simultaneously, means governed by the current of fuel mixture passing through said chamber for varying the opening of the valve with respect to the shutter, and means for controlling the temperature of the air in the inner air duct.

5. In a carburetor for an internalcombustion engine, a mixing chamber, a fuel duct opening therein, a pair of air ducts concentric with the fuel duct and opening into said chamber, means for heating the air led into the inner air duct, a throttle valve in the fuel duct, an iris shutter for throttling the inlet of air from said air ducts into the chamber, means for operating said valve and shutter simultaneously, means governedby the current-of fuel mixture passing through said chamber for varying the opening of the valve with respect to the shutter, and means for controlling the relative temperature of the air in the two ducts. i

6. In a carburetor for an internal combustion engine, a mixing chamber, a fuel duct opening therein, a pair of air ducts concentric with the fuel duct and opening into said chamber, means for heating the air led into the inner air duct,

' a throttle valve in the fuel duct, an iris shutter with respect to the shutter, and means including a thermostat in the heated air duct for controlling the temperature of the air passing through said duct.

7. In a carburetor for an internal combustion engine, a mixing chamber, a fuel nozzle having a central fuel inlet opening into the chamber, said nozzle being formed with laterally projecting arms and cups at the ends of said arms with fuel ducts leading to said cups, an air inlet sur rounding the fuel nozzle, a throttle valve in the fuel inlet, a shutter normally closing the air inlet and covering said cups, means for simultaneous opening the valve and the shutter in predetermined ratio, and means controlled by the current of fuel mixture passing through the mixing chamber for varying said ratio.

8. In a carburetor for an internal combustion engine, a mixing chamber, a fuel nozzle having a central fuel inlet opening into the chamber, said nozzle being formed with laterally projecting arms and cups at the ends of said arms with fuel ducts leading to the cups, said cups being of substantially triangular form, an air inlet into the chamber surrounding the fuel nozzle, a throttle valye in the fuel inlet, an iris shutter normally closing the air inlet and covering said cups, means for simultaneously opening the valve and the shutter in predetermined ratio,,and means controlled by the current of fuel mixture passing through the mixing chamber for varying said ratio.

9. In a carburetor for an internal combustion engine, a mixing chamber, a fuel nozzle having a central fuel inlet opening into'the chamber, said nozzle being formed with laterally projecting arms and cups at the ends of said arms with fuel ducts leading to said cups, an air inlet surrounding the fuel nozzle, a throttle valve in the IZACHARIAH s. HOFFMAN. 

